Automatic, computer controlled, embroidery machines for forming decorative needlework designs have been used for a number of years, particularly for placing embroidered logos, symbols and messages on baseball caps. A machine specifically adapted for embroidering designs on caps is described in U.S. Pat. No. 4,628,843, issued Dec. 16, 1986 to Ikuo Tajima. The Tajima machine has a table, moveable along a Y-axis, that carries a plurality of drivers each of which detachably support a holder for a single cap. One machine may have up to 18 of the drivers, each of which are rotatable about an axis parallel to the Y-axis to affect rotation of the holder and mounted cap in a direction transverse to the Y-axis, i.e., along an X-axis on the cap. A reciprocable needle is positioned at the intersection of the X and Y axes and embroiders the design on the cap as the cap is controllably moved in the X and Y directions. The needle places each stitch at a preselected position on the cap, determined by translation of the moveable table along the Y-axis, and individual rotation of each of the drivers supporting the cap holder to bring the cap embroidery area into the desired X-axis position. Such machines have been commercially successful and have enabled a wide range of designs and expressions to be attractively placed on a useful article of clothing.
However, it has been found that after such machines have been in operation for as short of a time as a few months depending on care and usage, that the quality of the embroidered design deteriorates. The image tends to become less distinct, sharp-lined features become somewhat jagged, and there is a noticeable overlap of adjacently disposed colored areas. It was believed that the problem resulted from a loss of tight engagement of the cap holder with its respective driver. In an effort to maintain a perceived better fixed relationship between the cap holder and its driver, a different mounting arrangement was proposed as described in U.S. Pat. No. 5,261,338, issue Nov. 16, 1993 to Ikuo Tajima et al.
However, it has been discovered that the interconnection between the cap holder and its driver is not the primary cause of quality deterioration in the embroidered design. The Tajima embroidery machine supports the cap driver on a pair of fixed rollers that contact an internal arcuate surface of the driver, and guide the driver by a pair of fixed rollers that ride in a groove formed in an external arcuate surface of the driver. During the embroidery operation, the grooves become contaminated with pieces of thread, dust, dirt and other debris. With each pass of a roller in the groove, the material in the groove is compacted on top of previously compacted debris. Since the rollers are fixed and cannot yield, the driver surfaces become distorted with the result that the driver no longer rotates smoothly or uniformly about the Y-axis to position the embroidery area of the cap in the proper X-axis registration. This causes jerking and displacement of the cap holder mounted on the driver, with the result that the needle stitch does not occur at its desired position. Also, because the rollers are made of a harder material than the mating groove, the sides of the groove wear. The additional groove width makes it difficult, if not impossible, to accurately control the Y-axis position of the driver assembly. Thus, it can be readily seen that when the above described wear or damage occurs, the operating position of the driver will be directly and adversely affected, resulting in decreased quality of the embroidered design.
Also, the rotation, and consequently the X-axis orientation of the embroidery area of each of the cap drivers is controlled by a connecting link between each driver and an actuating arm. Any resistance to movement or uneven motion by any one driver may be translated through the connecting link and actuating arm to other drivers, causing inaccurate positioning of other cap holders. Thus, each irregular movement, although primarily caused by a single driver, is easily multiplied.
Furthermore, it has been noted that when several drivers become difficult to move because of guide groove buildup and bending or distortion of the arcuate roller reaction surfaces on the drivers, the X-axis positioning motor becomes heated to a significantly higher temperature than normal. Also, the actuating linkage between the motor and the cap drivers show visible evidence of stress and excessive wear. Both of these conditions are a further indication that one or more of the cap drivers is binding and is not freely rotatable to the desired orientation.
The present invention overcomes the problems set forth above. It is desirable to have a cap driver that even after extended periods of operation is able to accurately and repeatedly produce a quality embroidered decorative design on a cap. It is also desirable to have a cap driver that is not prone to the collection and buildup of debris in a critical guide or support element. It is also desirable to have a cap driver that is not bent or damaged as a result of debris buildup between fixed position rollers and reaction surfaces on the cap driver.